Mannich condensation products of high molecular weight hydrocarbon-substituted phenols, aldehydes and reactive amines are known detergent-dispersants in lubricating oil and liquid hydrocarbon fuels. Their preparation and use are described in Otto, U.S. Pat. Nos. 3,368,972 and 3,649,229; Worrel, 3,413,374; and Piasek et al, 3,539,633 and 3,798,165.